Electrode Engineering for High-Durability Variable-Emissivity Devices Based on Reversible Copper Electrodeposition.

Abstract

Variable emissivity devices enable dynamic infrared emissivity modulation for thermal camouflage, energy-efficient architecture, spacecraft thermal control, and wearable thermoregulators. While reversible metal electrodeposition allows remarkable spectral modulation via controlled metal deposition/dissolution, electrode degradation-induced cycling instability hinders practical application. Ultra-thin Ir-based electrode strategy is developed to enhance durability of reversible copper electrodeposition variable-emissivity device. The Ir-electrode-enabled devices exhibit merely 11% degradation in radiative temperature variation after 8000 cycles and 23% attenuation in emissivity modulation after 6000 cycles, substantially outperforming Pt-based counterparts (54% attenuation after 5000 cycles). This stability stems from Ir's inherent chemical inertness, superior conductivity, and mechanical robustness, which collectively suppress stress-induced cracking, electrolyte corrosion, and electrochemical oxidation. Ir-Au grid composite electrode ensures homogeneous deposition/dissolution, maintaining performance in large-area rigid and flexible devices (>3000 cycles on 10 × 10 cm² rigid Si, >1000 cycles on 8 × 8 cm² flexible polyamide). Integration of Cr₂O₃ optical interference layer with Ir electrode on BaF₂ enables dual-band modulation (visible coloration and 3-14 µm infrared wavelength, emissivity modulation range Δε = 0.56) with stability exceeding 10 000 cycles. The Ir-based electrode engineering exhibits enhanced stability, scalable manufacturability, compliant substrate integration, and color-compatible operation, providing pivotal implications for thermal regulation systems, IR stealth applications, and advanced display technology.